Liquid detergent processes



LIQUID DETERGENT PROCESSES Filed Oct. 16, 1964 TIME IN MINUTES N N O 0''0 0 5 I.O L5 2.0 2.5 3.0 3.5

SPECIFIC VISCGSITY INVENTO R Arm R United 3,457,176 LIQUID DETERGENTPRGCESSES James M. Huggins, St. Ann, Mm, assignor to Monsanto Company,St. Louis, Mo., a corporation of Delaware Filed Oct. 16, 1964, Ser. No.404,404 lint. Cl. Clld 3/16 U.S. Cl. 252135 11 Claims ABSTRACT 6F THEDISCLOSURE The present invention relates to processes for manufacturingliquid detergent compositions. More particularly, the present inventionrelates to processes for manufacturing liquid detergent emulsioncompositions that exhibit excellent stability against phase separationeven though they contain relatively high concentrations of dissolvedinorganic salts and of synthetic organic detergent components.

The many benefits which can result from the utilization of effectivedetergent compositions that are liquid in form are widely appreciated.In order to be competitive with the Well-known dry powdered orgranulated detergents, liquid detergent compositions must contain highconcentrations of both inorganic builder salts; for example, phosphates,silicates, carbonates and sulfates, (usually dissolved in water); andorganic detergent active materials. Because of the presence ofhigh-concentrations of inorganic salts in water, very little, if any, ofthe organic detergent active material can actually be dissolved inwater. Therefore, if a detergent manufacturer wishes to make areasonably competitive liquid detergent, he must ordinarily eitherdisperse or emulsify the detergent active material into the concentratedsalt solution.

While the emulsification or dispersion per se of most detergent activematerials in concentrated salt solutions is not difficult, it hasheretofore been very difficult to manufacture liquid detergentscontaining such dispersed detergent active materials that are stable foran extended period of time against separation of the detergent activematerial from the concentrated salt portion of the detergent composition(i.e., stable against phase separation). Since consumers of liquiddetergents generally feel that liquid detergents which separate areobjectionable, it can readily be appreciated that manufacturers ofconcentrated liquid detergents have as one of their foremost objectivesthe production of liquid products that are stable against phaseseparation for as long a time as possible under any or all of the usualWarehousing, shipping and storage conditions to which the liquiddetergent compositions are exposed.

Because of the impracticability of testing thousands of detergentformulations under various end-use conditions in order to determinewhether or not a given formulation is of acceptable stability, a testwas devised to stimulate prolonged storage conditions. The results ofthis test were subsequently found to correlate well with data fromactual prolonged storage of the liquid detergent formulations tested.Briefly, the test involves centrifugation of the material (at about 30C.) under approximately 1000 tates Patent gravities for 60 minutes in acalibrated glass centrifuge tube. Formulations that exhibit less than 6%(by volume) visible separation in this very extreme test are consideredacceptable (and will exhibit excellent stability against phaseseparation under normal storage and handling conditions), while thosethat exhibit more than 6% separation are not acceptable. This test willbe described in greater detail in Example 1, below.

Relatively stable emulsions can be made, of course, if extremely highviscosity emulsions (i.e., having apparent viscosities of 1500centipoises or more) are produced. However, such high viscosityemulsions depend solely upon their visocisity for their stability, andare not desirable for liquid detergent emulsions because products havingsuch very high viscosity have poor pouring draining characteristics(from containers). The liquid detergent emulsions to which the presentinvention is directed are those having apparent viscosities of less than900 centipoises, as measured by a Brookfield viscometer using a number 3spindle, at 30 rpm. and at 25 C., and preferably having apparentviscosities of from about to about 800 centipoises.

The use of certain polymeric materials, and mixtures of certainpolymeric materials, to aid in the stabilization of liquid detergentemulsion compositions has been disclosed heretofore. For example, theuse of several specifled polymers is described in detail in U.S. PatentNo. 3,060,124. The polymers disclosed in this patent become effectivestabilizers when they are simply dissolved into or dispersed wellthrough the liquid detergent emulsion composition. The number ofpolymers that can act as effective stabilizers for liquid detergentemulsion compositions via simple dispersion and/or dissolution in thedetergent formulation is, however, very small. In addition, whether ornot a given polymer can perform as a stabilizer for liquid detergentemulsion compositions cannot presently be predicted in advance. Thepolymer must first be tested in an actual formulation before its valueas a stabilizer can be determined.

One class of polymeric material which is both relatively inexpensive andcommercially available is that known as the class of copolymers ofmethyl vinyl ether and maleic anhydride. Although copolymers of methylvinyl ether and maleic anhydride have been considered heretofore for useas stabilizers for liquid detergent emulsion compositions, no procedurewa s known heretofore whereby detergent compositions containingcommercially economical amounts of such copolymers could be stabilizedsufficiently to be considered acceptable in the aforementioned stabilitytest.

The invention claimed herein is based upon the discovery that unlesscritical limitations of method of processing the liquid detergentemulsion compositions are observed, the use of copolymers of methylvinyl ether and maleic anhydride in such compositions does not result inthe manufacture of commercially acceptably stable products; whereas byobserving these critical limitations, products are obtained which aresurprisingly stable, even under the very extreme conditions of theabove-described test.

Thus, it has been discovered that unless certain critical processlimitations are observed with respect to (1) hydrolysis of thecopolymers of methyl vinyl ether and maleic anhydride and (2) partialesterification of the hydrolyzed copolymers; which process limitationsinvolve time, temperature and pH of the systems involved; excellentemulsion stability cannot be obtained by use of such copolymers, whereasby following certain critical limitations (which will be detailedhereinafter), very stable liquid detergent emulsions can be obtained.

The unexpectedly high emulsion stability that results from practicingthe present invention results when: (a)

r :3 certain copolymers of methyl vinyl ether and maleic anhydride arefirst partially hydrolyzed by treatment with water under carefullycontrolled conditions of temperature and pH for a certain criticalperiod of time; (b) the resulting (partially) hydrolyzed copolymer isreacted with a surfactant (via a partial esterification reaction)containing at least one reactive hydroxyl radical in its molecule undercarefully controlled, critical conditions of temperature, pH and time(while at least part of said surfactant is being maintained in anemulsified condition-dispersed in an aqueous continuous phase); andsubsequently (c) bringing the pH of the resulting partially esterifiedaqueous emulsion to aboove about 8.5, preferably into the range of fromabout 9.5 to about 10.5.

The copolymers (or interpolymers) of vinyl methyl ether and maleicanhydride useful in the practice of this invention are those reactionproducts of the following reaction:

having specific viscosities (measured in the usual way by dissolving 1part by weight of the essentially anhydrous copolymer in 99 parts byweight of dimethylforrnamine, and subsequently measuring the specificviscosity of the resulting solution at 25 C. by modification of ASTMmethod D445446T, method B, using an Ostwall viscometer), between about0.5 and 3.5. The molecular weight of such copolymers may range fromabout 400 to more than 2 million.

The synthetic organic detergents that have been found especially usefulin the practice of the present invention are those which are watersoluble (i.e., soluble in water at room temperature to the extent of atleast about 0.1 to 0.3 weight percent, which is about the concentrationat which detergents are generally utilized to wash clothes or dishes,for example) and contain at least one hydroxyl group attached directlyto a carbon atom (through an O-C bond). They can be either nonionic oranionic in nature, but of these, the nonionic synthetic organicdetergents are preferred. The general class of water-soluble nonionicand anionic synthetic organic detergents (that contain at last onehydroxyl group in their molecule) is well-known by those skilled in theart and include, for example, condensation products resulting from theinterreaction of one or more lower alkylene oxides (such as ethyleneoxide, propylene oxide, butylene oxide, butylene dioxide,epichlorohydrin, isobutylene oxide, and the like) with a compound havingwhat is termed at least one reactive hydrogen" [such as, for example,alkylphenols including nonylphenol, dodecylphenol, octylphenol,dinonylphenol, diisopropylphenol, diamylphenol, dibutylphenol, as wellas other alkylphenols wherein the alkyl group (or groups) contain atotal of from about 4 to about 20 carbon atoms; alkyl cesols, whereinthe alkyl group (or groups) contain a total of from about 4 to about 20carbon atoms; alcohols containing from about 6 to about 30 carbon atoms(such as lauryl alcohol, mixed cocoanut alcohols, oxotridecyl alcohol,oleyl alcohol, hydrogenated tallow alcohols, and the like); the alkylmercaptans such as dodecylmercaptan, tridecylmercaptan,octadecylmercaptan and the like, wherein the alkyl group contains fromabout 8 to about 25 carbon atoms; aliphatic amides such astridecylamide, hexadecylamide, nonylamide, and the like, wherein theamide contains from about 6 to about 30 carbon atoms; alkyl or aliphaticsulfonamides such as dodecylsulfonamide, tetradecylsulfonamide,tetradecenylsulfonamide and the like, wherein the aliphatic or alkylradical contains from about 8 to about 24 carbon atoms; thepolypropylene oxides and polybutylene oxides having molecular weights offrom about 750 to about 4000; reaction products of propylene oxide and/or butylene oxide with polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine and the like, which reaction productshave molecular weights of from about 750 to about 4000; productsresulting from the condensation of a lower alkylolamine (such asmonoethanolamine, diethanolamine, dimethylolamine, isopropanolamine,di-n-propanolamine, and the like) with a fatty acid containing fromabout 8 to about 24 carbon atoms], as well as many other materials.

Examples of water-soluble anionic synthetic organic detergents have therequisite hydroxyl radical in their molecule include thehydroxy-substituted fatty acids (such as alpha-hydroxy stearic acid,beta-hydroxy oleic acid, 4-hydroxy lauric acid, and the like); esters offatty acids that contain between 8 and 24 carbon atoms (wherein therequisite hydroxyl radical can be in either the fatty acid or thealcohol portion of the molecule); as well as many other anionicmaterials.

The foregoing examples of nonionic and anionic synthetic organicdetergents are by no means exhaustive of those that can be usedsuccessfully in the practice of the present invention. Thus, anysurfactant (detergent) that has a hydroxyl group in its molecule and issulficiently Water soluble can be used in the practice of the presentinvention. Many other materials that meet these qualifications canreadily be found in Schwarz and Perrys two books: Surface Active Agents,volumes I and II, Interscience Publishers, New York (1958 and 1959).

Minor proportions (as compared to the amount of the polyoxyalkylenedetergent active materials that are utilized) of other detergentmaterials can be used to supplement the above-described polyoxyalkylenedetergentactive materials in the practice of the present invention.Typical of these other types are the detergent active or surface activearomatic sulfonates which are free of polyoxyalkylene chains, such asthe sodium sulfonate of an alkylated aromatic hydrocarbon. Thesesulfonates are usually prepared by alkylating an aromatic hydrocarbon ofthe class consisting of benzene, toluene, xylene, for example, withaliphatic or olefinic hydrocarbons having from 9 to 18 carbon atoms, andthen sulfonating and neutralizing the resulting alkylaromatichydrocarbon. Another example of detergent-active materials that cansupplement the polyoxyalkylene detergent-active materials describedhereinbefore are the alkylolamides having from 10 to 20 carbon atoms inthe acid portion of the molecule. These alkylolamides are formed byreacting of fatty acid, such as tall oil fatty acid, coconut fattyacids, stearic acid, lauric acid, etc., with an alkylolamine such asmonoethanolamine, diethanolamine, monoisopropanolamine,diisopropanolamine, mono -npropanolamine, di-n-propanolamine, etc.Ordinarily, these supplemental (to the hydroxyl-containing materials)detergent active materials can be utilized in the compositions withinthe scope of this invention at levels of from a mere trace to severalweight percent. However, the preferred liquid detergent compositionscontain no more than about 60 weight percent of such supplementalmaterials based on the hydroxyl-containing detergent active materialemployed.

One can employ in the practice of this invention, a solution of anyinorganic or organic water-soluble salt which it is desired for buildingor for any other reason, to incorporate into a detergent composition, solong as the salt is compatible with the other components of thecomposition. Well-known precautions should be observed in mixing thevarious materials in the practice of the invention. Ordinarily, thecompatible salts that can be employed are those which are soluble indistilled water to the extent of at least about 5 weight percent. Andwhere raw material cost considerations are important, these salts willbe inorganic in nature. As a practical matter, however, because ofeconomic considerations as well as the necessity to include in theliquid detergent compositions as high a level as is practicable ofmaterials which can sequester hardness ions, such as calcium, magnesium,and iron, the salts which are preferably utilized are the alkali metalchain phosphate salts (such as, for example, the alkali metalpyrophosphates such as tetrasodium pyrophosphate, tetrapotassiumpyrophosphate, etc.), the acid pyrophosphates such as disodiumpyrophosphate, trisodium monohydrogen pyrophosphate, dipotassiumdihydrogen pyrophosphate, etc., the tripolyphosphates and acidtripolyphosphates such as sodium tripolyphosphate (Na P O potassiumtripolyphosphate (K P O tetrasodium monohydrogen tripolyphosphate (K HPO tripotassium dihydrogen tripolyphosphate (K H P O etc., the alkalimetal tetrapolyphosphates such as hexasodium and hexapotassiumtetrapolyphopshate, etc., the alkali metal hexametaphosphates and higherchain length chain polyphosphates such as those that are present in thesodium, potassium, and lithium phosphate glasses (usually prepared bymelting a mixture of phosphate salts having an M O/P O ratio betweenabout 1.0 and about 1.3 Where M is an alkali metal, and quenching theresulting product to yield a mixture of chain polyphosphate salts ofvarying molecular weight), and the like (wherein the particularlypreferred alkali metal salts are potassium and sodium). Of these,tetrapotassium pyrophosphate is most preferred. Other water-solubesequestering agents such as alkali metal ethylene diamine, alkali metalcitrate, alkali metal tartrate, etc., can also be utilized to advantagein the composition. It should be understood that while reference hereinis made specifically to the alkali metal chain phosphate salts, otherinorganic salts, and water-soluble sequestering agents can generally beutilized either in place of all of the phosphate salt, in place of someof it, or in addition to it.

Another ingredient which can be utilized along with the above describeddetergent compounds and chain-polyphosphates in the aqueous detergentsolutions prepared according to this invention are the water-solublesodium and potassium silicates. As is well-known, sodium silicates canvary quite widely in composition, ranging from tetraand disilicateshaving a mol ratio of Na O:SiO of 1:4 and 1:2, respectively, to the morealkaline silicates, such as the orthosilicates having a mol ratio .of NaO:SiO of 2:1. In general, potassium silicate (K O:SiO 1:2.1) is thepreferred compound silicate for use according to the present invention.However, other silicates, or mixtures of silicates, having overall molratio of Na O:SiO between about 1:1 and 1:4 may be used.

Inorganic alkali metal carbonates can also be employed. The carbonatesemployed are preferably the potassium carbonates such a commercial pearlash or modified potassium carbonates having various degrees ofalkalinity. Minor amounts of additional ingredients, such as borax, Na BO -10H O and potassium or ammonium borates, dyes, perfumes, etc., canalso be incorporated into the liquid detergent. Additionally, theultimate concentrate mixture is preferably formulated so that an aqueoussolution of about 0.25 weight percent has a pH of between about 8.5 andabout 10.5.

The particular quantities of any of the aforementioned materials (otherthan the special surfactant that is reacted with the copolymer of vinylmethyl ether and maleic anhydride, and the copolymer itself) that areutilized in the liquid detergent emulsions that are made in accordancewith the processes of the present invention are not critical: anyparticular material being present in a given detergent formulation inaccordance with the particular end use intended for the stabilizeddetergent composition. However, for general purpose detergent usage, thefollowing practice is suggested. In making up liquid detergent emulsionsaccording to the present invention, the aforementioned ingredients can,for example, be utilized in the following proportions: (1) from about 1to about 25, and preferably from about 3 to about 15 percent by weightof active detergent compound; (2) from about 10 to about 50, andpreferably from about 15 to about 25 percent by weight of phosphate; (3)from 0% to 10%, and preferably from about 2% to about 8% ofWater-soluble silicate (calculated on the basis of anhydrous silicatematerial); all of these percentages being based upon the final liquiddetergent composition.

The liquid formulations of the present invention generally contain fromabout 30% to about 75% and preferably from about 40% to about by weightof water based upon the total liquid detergent. Alcohols, such asethanol and glycols, such as ethylene glycol or propylene glycol may asobe employed in the present detergent compositions, if necessary toimprove the compatibility of the various components over a wide range oftemperature conditions. The proportion of alcohol or glycol may be from1% to 10% by weight.

The present products have been found to be of particular utility inautomatic washers as a liquid concentrate, which is readily pumpedthrough pipes and tubing into the washing chamber. These compositionsmay be stored for prolonged periods of time without separation intoorganic and inorganic layers. This is essential in the pro duction of aliquid detergent which is to be utilized in small increments during along period of storage.

The reasons for the unexpectedly superior stability of the liquiddetergent emulsions that are prepared in accordance with the processesof this invention are not known. It is a fact, however, that whencritical process limitations outlined hereinbefore are observed,exceptionally stable, valuable liquid detergent emulsions result. Thepresent processes can be divided for the sake of clarity into threedistinct steps; namely, (1) hydrolysis, (2) esterification, and (3)pH-raising. Although in the following discussion, these various stepswill be described separately, it will be understood that the overallprocesses of this invention can be performed in both batch andcontinuous types of operations.

The hydrolysis step of the present processes must be performed while thecopolymer is dispersed through (or maintained completely in contact withthe Water therein in some other manner) a liquid aqueous medium having apH below 4.5 (preferably from about 2.5 to about 4). In addition, thetemperature of the acidic aqueous medium or solution must be betweenabout C. and about 105 C. (preferably between about C. and about C. foroptimum results) for a certain critical period of time, which period oftime has been found to vary somewhat depending upon the specificviscosity of the particular copolymer being employed. At temperaturesbelow this critical range, the necessary type of hydrolysis of thecopolymer apparently does not occur, or occurs so slowly as to make anyprocess resulting from use of such low hydrolysis temperatureimpractical. The critical period of time referred to above can actuallyvary to a relatively small extent (generally within an overall range ofabout 5 minutes) for the particular copolymer being employed. Thus, inthe figure of the drawings, any point within the area designated ABCDAwhich falls upon the vertical line corresponding to the specificviscosity of the particular copolymer employed represents the criticalperiod of time mentioned above, While the point (on such vertical line)falling upon the heavy black line bisecting area ABCDA in the figurerepresents an approximately optimum time condition. Note that theabovedescribed hydrolysis step apparently does not result in completehydrolysis of the copolymer (since the use of substantially longerhydrolysis periods than those designated aboveother factors beingequalresults in final liquid detergent emulsions that do not have theexcellent stability of those made via the processes of this invention).

The esterification step of the present processes involves essentiallythe intermixing a quantity or an amount of a surfactant that is capableof reacting with the hydrolyzed groups (apparently the free carboxylicacid groups) on the partially hydrolyzed copolymer (resulting from thehydrolysis step described above) to form ester groups. Thus thesurfactant must contain at least one free hydroxyl group. Reactivesurfactants of this type are described in detail hereinbefore. Anyamount of such reactive surfactant can be used during thisesterification step within the range of from about 0.1 to about 25weight percent, based on the total weight of the resultingesterification mixture (containing the partially hydrolyzed copolymer,the surfactant, and the aqueous medium); but apparently more than thatamount of reactive surfactant necessary to saturate the aqueous mediummust be present during the esterification step. Preferably, the amountof surfactant should be within the range of from about 0.5 to about 12weight percent during the esterification step. In addition, thetemperature and the pH of the aqueous medium should be closelycontrolled for a certain critical period of time during theesterification step. Thus, the temperature must be maintained within therange of from about 70 C. and about 105 C. (preferably between about 70C. and about 95 C. for optimum results, and the pH of the aqueous mediummust be below about 8 (preferably between about 3 and about 7.5) duringthis critical period of time.

The critical period of time referred to with respect to theesterification step of the present processes can vary to some extent(generally within an overall range of about minutes) the particularrange being determined by the particular copolymer involved; generallyhigher molecular weight copolymers require shorter esterification times.Thus, any point Within the area designated EFGHIJE in the figure of thedrawings which falls upon the vertical line corresponding to thespecific viscosity of the particular copolymer employed represents suchcriti cal period of (ester-ification) time, while the point (on suchvertical line) falling upon the heavy black line bisecting area EFGHIIEin the figure represents an approximately optimum time condition for thegiven copolymer. Only partial esterification of the acidic (partiallyhydrolyzed) copolymer occurs during the above-described esterificationstep.

During the hydrolysis and esterification steps detailed above the pH ofthe aqueous medium can be maintained in any desired manner. For example,organic or inorganic acids can be resent in the aqueous medium in orderto help maintain the desired acidic pH during the acidic hydrolysisstep, and even during the esterification step. The presence of othermaterials in the aqueous medium apparently has no deleterious effect onthe overall desired reactions so long as the pH conditions detailedabove are met (and so long as there is enough water present in eachinstance to maintain the aqueous medium in the liquid or fluidcondition). Also, the esterifica tion step need not be performedimmediately after the hydrolysis" step. Thus, if desired, the aqueousmedium containing th partially hydrolyzed copolymer (resulting from thehydrolysis step) can be preserved for prolonged periods of time andtemperatures significantly below about 70 C. (preferably below about 50C.) without significantly destroying the ability of the partiallyhydrolyzed copolymer to react With the surfactant when it issubsequently utilized under esterification conditions (described above).Similarly, the hydrolysis and esterification steps can be interrupted bycooling the aqueous medium, for example, Without destroying theseadvantageous processes, so long as the overall hydrolysis times andesterification times (in accordance with the drawings) under thecritical conditions described above are ultimately observed, or at leastso long as the desired extent of hydrolysis and esterification havetaken place.

The name of the so-called pH-raising step of the present processesimplies what actually must occur in order to finish off the stabilizedliquid detergent emulsions of this invention. During this step the pH ofthe aqueous medium (containing the partially esterifiedcopolymer-surfactant mixture) is raised to at least about 8.5, therebypreventing any additional acidic hydrolysis or esterification fromoccurring. Apparently, it is only the raising of the pH which iscritical during this step of the processes of the present invention. Anybasic material that is capable of raising the pH of the aqueous mediumresulting from the above-described esterification step to above about8.5 when it is simply intermixed therewith can be used. Hundreds ofmaterials having such capability are well-known to those skilled in theart, and need not be detailed here. For example, any of theabovedescribed alkali metal polyphosphate salts that are basic in nature(have no free acidic groups) can be used. Of these, tetrapotassiumpyrophosphate and potassium tripolyphosphate are particularly preferred.By use of such basic, water-soluble polyphosphate salts to adjust the pHof the aqeuous media (containing the partially esterified polymer) toabove about 8.5, a double purpose is served; the resulting solution thenalready contains builder salts, if such builder salts are desiredtherein. Additional surfactant can be either dissolved or emulsifiedinto the aqueous medium either before or during this pH-raising step.

In the following examples, which illustrate some of the preferredembodiments of the present invention, all parts given are by weightunless otherwise stated.

Example I Into a conventional jacketed (for water cooling or steamheating) stainless steel mixing vessel fitted with a high speed,6-bladed, turbine-type agitator (wherein the diameter of the turbineblades is about one-half the diameter of the mixing vessel) are poured2990 parts of Water. The water is heated to about C. While mixingsteadily, 80 parts of a powdered, anhydrous copolymer of vinyl methylether and maleic anhydride (having a specific viscosity of 0.5) areadded slowly over a 2 minute period of time. In a hydrolysis step, theresulting mixture is then stirred at 80 C. for an additional 14 minutesin order to partially hydrolyze the copolymer.

Into the resulting acidic mixture are then added (over 1 minute of timeand with very intense agitation) a mixture (preheated to about 80 C.) of300 parts of disodium dihydrogen pyrophosphate and 1100 parts of anadduct of dodecylphenol and ethylene oxide. (The adduct was made bycondensing 10 moles of ethylene oxide with one mole of dodecylphenol.)In an esterification step, the resulting emulsion is then continuouslystirred at about 80 C. for 30 minutes. Then 4110 parts of a 60 weightpercent aqueous solution of tetrapotassium pyrophosphate are added tothe partially esterified emulsion over about 3 minutes, after which 550parts of a 45 weight percent aqueous solution of potassium hydroxide areadded. Addition of the KOH results in a slight increase in temperatureto about 86 C. The resulting mix is then cooled to about 81 C., and 800parts of a 35 weight percent aqueous solution of sodium silicate (NaO/SiO =2.4) are added over 2 minutes time. The resulting mixture is thenstirred for an additional 5 minutes, cooled to about 40 C., and packagedfor sale to the ultimate consumers. Its pH is 10.2.

The stability of the product is then tested by subjecting 200 mls. of itin a calibrated centrifuge tube to 1000 times gravity in a conventionalcentrifuge for one hour. At the end of this test, only 4 volume percentof clear solution is observed at the bottom of the centrifuge tube. Thusseparation in this test is only 4 volume percent, the product is ratedacceptable, in accordance with the foregoingdiscussion.

Still another test to which the product is subjected is a storage testin an oven held at 50 C. for six weeks. The

product is found to be stable in this test, also; showing no visiblesign of phase separation after being stored for this period of time.

In a manner practically identical to that of Example I above, severalother anhydrous copolymers of vinyl methyl ether and maleic anhydrideare utilized for the manufacture of phase-stabilized liquid detergentemulsions. Data therefor is shown in table below. Hydrolysis Time andEsterification Time in table correspond to the amount of time,respectively, allotted for the hydrolysis step and the esterificationstep designated as such in Example I.

TABLE I Hydroly- Esterifica- Percent Specific 1 sis time tion time phase2 Stability 3 Example viscosity (min) (min) separation at 50 C.

0. 8 19 25 3 Excellent.

1 Specific viscosity of the copolymer used.

2 Volume percent.

3 Test conducted at 50 C. for 6 weeks. Excellent rating given when lessthan 5 volume percent of separation occurs during test.

What is claimed is:

1. A process for manufacturing a liquid detergent composition, whichprocess comprises the steps of (a) preparing an acidic aqueous polymerdispersion by partially hydrolyzing a copolymer of vinyl methyl etherand maleic anhydride having a molecular weight of above 400 with water;said hydrolysis being conducted at a temperature between about 70 C. and105 C. and under acidic conditions the amount of said copolymer beingfrom about 0.3 to about 5 weight percent of said acidic aqueous polymerdispersion;

(b) intermixing to form an emulsion with said acidic aqueous polymerdispersion an amount of a synthetic organic detergent active materialcontaining at least one hydroxyl radical selected from the groupconsisting of anionic detergent active materials, nonionic detergentactive materials and mixtures thereof; said amount being more thanenough to saturate the resulting mixture and being from about 0.1 toabout weight percent, based on the total weight of said resultingmixture;

(c) converting said resulting mixture into an aqueous esterified polymerdispersion by maintaining the temperature of said resulting mixturebetween about 70 C. and about 105 C. and the pH of said resultingmixture below 8 until the partially hydrolyzed acidic copolymer of vinylmethyl ether and maleic anhydride has been partially esterified byreaction with said synthetic organic detergent active material; and

(d) thereafter raising the pH of the resulting emulsion composition toat least about 9:

wherein the amount of time during which steps (a) and (c) are carriedout falls within the areas designated ABCDA and EFGHIJE, respectively,in FIGURE 1, depending upon the specific viscosity of said copolymer ofvinyl methyl ether and maleic anhydride; said specific viscosity beingfrom about 0.5 to about 3.5.

2. A process for manufacturing a liquid detergent 10 emulsioncomposition, which process comprises the steps of (a) intermixing withwater from about 0.3 to about 5 weight percent, based on the weight ofthe resulting first mixture, of a copolymer of vinyl methyl ether andmaleic anhydride having a specific viscosity between about 0.5 and about3.5 and a molecular weight above about 400*, the pH of said resultingfirst mixture being from about 2.5 to about 4;

(b) partially hydrolyzing said copolymer to thereby form an acidicaqueous dispersion by maintaining the temperature of said resultingfirst mixture at from about 75 C. to about C. for a first period oftime;

(c) forming a liquid emulsion by intermixing with said resulting firstmixture from about 0.5 to about 12 weight percent, based on the weightof said liquid emulsion, of a nonionic synthetic organic detergentcontaining at least one hydroxyl radical to thereby form a secondmixture; the pH of said second mixture being from about 3 to about 7.5;

(d) reacting together the partially hydrolyzed copolymer in said secondmixture and said nonionic synthetic organic detergent to thereby form anesterified emulsion by maintaining the temperature of said secondmixture between about 70 C. and about for a second period of time whilesaid nonionic synthetic organic detergent is retained in an emulsifiedcondition;

(e) thereafter increasing the pH of said esterified emulsion to betweenabout 9 and about 11; and blending into said esterified emulsion fromabout 15 to about 30 weight percent, based on the weight of saidemulsion composition, of an inorganic watersoluble potassiumpolyphosphate salt; said first period of time being within the areadesignated ABCDA in FIGURE 1 and said second period of time being withinthe area EFGHIJE in FIGURE 1; the particular periods of time beingdependent upon the specific viscosity within the range of from about 0.5to about 3.5 of said copolymer of vinyl methyl ether and maleicanhydride.

3. A process as in claim 2, wherein the specific viscosity of saidcopolymer is between about 0.75 and about 1, said first period of timeis from about 17.5 to about 22.5 minutes, and said second period of timeis from about 22.5 to about 27.5 minutes.

4. A process as in claim 2, wherein the specific viscosity of saidcopolymer is between about 1 and about 1.25, said first period of timeis from about 22.5 to about 27.5 minutes, and said second period of timeis from about 18 to about 23 minutes.

5. A process as in claim 2, wherein the specific viscosity of saidcopolymer is between about 1.25 and about 1.50, said first period oftime is from about 25 to about 30 minutes, and said second period oftime is from about 15 to about 20 minutes.

6. A process as in claim 2, wherein the specific viscosity of saidcopolymer is between about 1.5 and about 1.75, said first period of timeis from about 28 to about 33 minutes, and said second period of time isfrom about 12 to about 17 minutes.

7. A process as in claim 2, wherein the specific viscosity of saidcopolymer is between about 1.75 and about 2, said first period of timeis from about 32 to about 37 minutes, and said second period of time isfrom about 7.5 to about 12.5 minutes.

8. A process as in claim 2, wherein the specific viscosity of saidcopolymer is between about 2 and about 2.25, said first period of timeis from about 34 to about 39 minutes, and said second period of time isfrom about 6 to about 12 minutes.

9. A process as in claim 2, wherein the specific viscosity of saidcopolymer is between about 2.25 and about 2.5, said first period of timeis from about 37 to about 42 minutes, and said second period of time isfrom about 6 to about 12 minutes.

10. A process as in claim 2, wherein the specific viscosity of saidcopolymer is between about 2.5 and about 2.75, said first period of timeis from about 39 to about 5 44 minutes, and said second period of timeis from about 6 to about 12 minutes.

11. A process as in claim 2, wherein the specific viscosity of saidcopolymer is between about 2.75 and about 3, said first period of timeis from about 42 to about 47 minutes, and said second period of time isfrom about 6 to about 12 minutes.

12 References Cited UNITED STATES PATENTS 2/1966 Tuvell 252135 6/1967Grifo 252137 US. Cl. X.R. 252-156

